OFFSITE 2007 - The Green House
The BRE's OFFSITE2007 event was designed to explore the combination of modern construction methods and advanced technologies. 6 Houses were built, each by a different developer. Designs were required to achieve a Code for Sustainable Homes rating greater than 3, use MMC within the construction process and provide an environment for testing and monitoring innovative technologies.
Not surprisingly, in these still early days of designing for mass construction, a range of solutions involving massing, layout and construction, was created. The usual lightweight v heavyweight exchange was evenly matched but with some evidence that lightweight designs are taking on-board the thermal mass argument through providing a combination of heavy-weight flooring / thermal mass enhancing wall linings and the ever-so-new (and expensive) phase change materials (PCMs).
Perhaps because of the brief requirment, there was plenty of the usual bolted-on technologies to be seen. But where there appeared to be a consensus, it was in the growing recognition of the need for controlled ventilation in the upper ratings of the Code. MVHR units are to be found squirreled away in cupboards and roof spaces accompanied by increasingly complex arrays of environmental control systems. What will prove interesting will be the 'in-use' effectiveness of controlled ventilation combined with natural ventilation through 'stack effect' features in more than one of the houses - along with the very natural insinct for occupiers to throw-open the windows.
Unsurprisingly too, was the achievement of universally low elemental u-values. But thermal performance is more than speciflying materials - there was much evidence of piping of large amounts of mastic sealant into joints between components, evidence perhaps of the still bigger gap between theory and on-site practice. It is this disparity that is likely to prove the construction industry's big challenge in the long term.
The Green House
Winner of the 2007 Home for the Future Design Award Developer: Barratt Development PLC
Architects: Gaunt Francis Architects
House type: 3 bed detached house (can be implemented as semi or terraced)
Construction: Aircrete masonry blocks using thin-joint mortar, concrete floor slabs, SIP roofing, thin coat render, pre-patinated copper cladding
Code for sustainable Homes rating: 6
Heating system: MVHR, solar panel and electrical DHW.
Other features:
• Flexible planning enabling a variety of use scenarios
• Automatic window shutters providing solar control
• ‘Smart’ technology
• Sedum green roof
• Night-time ‘purge’ ventilation in summer through ‘stack effect’.
• Click on the thumbnails below to expand images
